2,951 research outputs found
N-(4-Butanoyl-3-hydroxyphenyl)butanamide
The title compound, C14H19NO3, was prepared via the intramolecular rearrangement of 3-(butanoylamino)phenyl butanoate in the presence of anhydrous aluminium chloride. The near coplanarity of the aromatic ring, the amide group and the carbonyl group of the butanoyl fragment [N—C—C—C = −179.65 (17) and O—C—C—C = −178.34 (17)°] results from the intramolecular O—H⋯O and C—H⋯O hydrogen bonds. In the crystal, the molecules form a one-dimensional polymeric structure via N—H⋯O interactions between their amide groups
Two-pole structures demystified: chiral dynamics at work
In the past two decades, one of the most puzzling phenomena discovered in
hadron physics is that a nominal hadronic state can actually correspond to two
poles on the complex energy plane. This phenomenon was first noticed for the
, and then for and to a less extent for
. In this Letter, we show explicitly how the two-pole structures
emerge from the underlying chiral dynamics describing the coupled-channel
interactions between heavy matter particles and Nambu-Goldstone bosons. In
particular, the fact that two poles appear between the two dominant coupled
channels can be attributed to the particular form of the leading order chiral
potentials of the Weinberg-Tomozawa form. Their lineshapes overlap with each
other because the degeneracy of the two coupled channels is only broken by
explicit chiral symmetry breaking of higher order. We predict that for
light-quark~(pion) masses heavier than their physical values, the two-pole
structures disappear, which can be easily verified by future lattice QCD
simulations. Furthermore, we anticipate similar two-pole structures in other
systems, such as the isopin coupled channel,
which await for experimental discoveries.Comment: 5 pages, 4 figure
Understanding the organic micropollutants transport mechanisms in the fertilizer-drawn forward osmosis process
© 2019 Elsevier Ltd We systematically investigated the transport mechanisms of organic micropollutants (OMPs) in a fertilizer-drawn forward osmosis (FDFO) membrane process. Four representative OMPs, i.e., atenolol, atrazine, primidone, and caffeine, were chosen for their different molecular weights and structural characteristics. All the FDFO experiments were conducted with the membrane active layer on the feed solution (FS) side using three different fertilizer draw solutions (DS): potassium chloride (KCl), monoammonium phosphate (MAP), and diammonium phosphate (DAP) due to their different properties (i.e., osmotic pressure, diffusivity, viscosity and solution pH). Using KCl as the DS resulted in both the highest water flux and the highest reverse solute flux (RSF), while MAP and DAP resulted in similar water fluxes with varying RSF. The pH of the FS increased with DAP as the DS due to the reverse diffusion of NH4+ ions from the DS toward the FS, while for MAP and DAP DS, the pH of the FS was not impacted. The OMPs transport behavior (OMPs flux) was evaluated and compared with a simulated OMPs flux obtained via the pore-hindrance transport model to identify the effects of the OMPs structural properties. When MAP was used as DS, the OMPs flux was dominantly influenced by the physicochemical properties (i.e., hydrophobicity and surface charge). Those OMPs with positive charge and more hydrophobic, exhibited higher forward OMP fluxes. With DAP as the DS, the more hydrated FO membrane (caused by increased pH) as well as the enhanced RSF hindered OMPs transport through the FO membrane. With KCl as DS, the structural properties of the OMPs were dominant factors in the OMPs flux, however the higher RSF of the KCl draw solute may likely hamper the OMPs transport through the membrane especially those with higher MW (e.g., atenolol). The pore-hindrance model can be instrumental in understanding the effects of the hydrodynamic properties and the surface properties on the OMPs transport behaviors
Production of and in decays as and molecules
The molecular nature of and have been
extensively studied from the perspective of their masses, decay properties, and
production rates. In this work, we study the weak decays of and by
invoking triangle diagrams where the meson first decays weakly into
and (), and then the
and are dynamically generated by the
final-state interactions of and via
exchanges of and mesons. The obtained absolute branching
fractions of Br are in reasonable
agreement with the experimental data, while the branching fractions of Br are smaller than the experimental central
values by almost a factor of two to three. We tentatively attribute such a
discrepancy to either reaction mechanisms missing in the present work or the
likely existence of a relatively larger component in the
wave function.Comment: 17 pages, 4 figure
Unlocking the Power of Open Set : A New Perspective for Open-Set Noisy Label Learning
Learning from noisy data has attracted much attention, where most methods
focus on closed-set label noise. However, a more common scenario in the real
world is the presence of both open-set and closed-set noise. Existing methods
typically identify and handle these two types of label noise separately by
designing a specific strategy for each type. However, in many real-world
scenarios, it would be challenging to identify open-set examples, especially
when the dataset has been severely corrupted. Unlike the previous works, we
explore how models behave when faced with open-set examples, and find that
\emph{a part of open-set examples gradually get integrated into certain known
classes}, which is beneficial for the separation among known classes. Motivated
by the phenomenon, we propose a novel two-step contrastive learning method CECL
(Class Expansion Contrastive Learning) which aims to deal with both types of
label noise by exploiting the useful information of open-set examples.
Specifically, we incorporate some open-set examples into closed-set classes to
enhance performance while treating others as delimiters to improve
representative ability. Extensive experiments on synthetic and real-world
datasets with diverse label noise demonstrate the effectiveness of CECL
Integrated Filtering Microstrip Duplex Antenna Array with High Isolation
This paper presents a 2 × 1 integrated filtering microstrip duplex antenna array with high isolation and same polarization. The antenna consists of two radiating patches fed by two T-shaped probes and a power distributing duplex network (PDDN). The PDDN is composed of two bandstop filters and a 180-degree phase shift power divider. And the PDDN is designed to achieve the functions of power division, frequency selectivity, and port isolation. A Transmission Line (TL) model is adopted to design the PDDN, and the detailed synthesis procedure is presented. For demonstration, the proposed antenna is designed and fabricated. The implemented antenna achieves an average gain of 10 dBi, a cross-polarization ratio of 20 dB, and an isolation of 35 dB within the operation band
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